U.S. patent number 9,498,590 [Application Number 13/783,916] was granted by the patent office on 2016-11-22 for leak detection system and method for tube or catheter placement.
This patent grant is currently assigned to SONARMED, INC.. The grantee listed for this patent is SONARMED, INC.. Invention is credited to Andrew D. Cothrel, Laura L. Lyons, Jeffrey P. Mansfield.
United States Patent |
9,498,590 |
Mansfield , et al. |
November 22, 2016 |
**Please see images for:
( Certificate of Correction ) ** |
Leak detection system and method for tube or catheter placement
Abstract
The present disclosure relates to a leak detection system and
method for tube or catheter placement. The system and method
includes acoustically sensing a leak in the seal between a tube or
catheter within a body and the body cavity against which it is
sealed, assisting the user in adjusting the system until the leak
has been substantially sealed, and establishing system parameters
to be used thereafter to maintain the system in an operating state
that will substantially prevent leakage, all using a noninvasive
acoustic technique.
Inventors: |
Mansfield; Jeffrey P.
(Indianapolis, IN), Cothrel; Andrew D. (Indianapolis,
IN), Lyons; Laura L. (Indianapolis, IN) |
Applicant: |
Name |
City |
State |
Country |
Type |
SONARMED, INC. |
Carmel |
IN |
US |
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Assignee: |
SONARMED, INC. (Carmel,
IN)
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Family
ID: |
49042104 |
Appl.
No.: |
13/783,916 |
Filed: |
March 4, 2013 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20130228171 A1 |
Sep 5, 2013 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61606679 |
Mar 5, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M
16/021 (20170801); A61M 16/0006 (20140204); A61M
16/0003 (20140204); A61M 5/5086 (20130101); A61M
16/044 (20130101); A61M 16/0051 (20130101); A61M
5/16831 (20130101); A61M 2205/502 (20130101); A61M
2205/3375 (20130101); A61M 25/10188 (20131105); A61M
2205/581 (20130101); A61M 2205/15 (20130101); A61M
2016/0027 (20130101) |
Current International
Class: |
A61M
16/00 (20060101); A61M 16/04 (20060101); A61M
5/50 (20060101); A61M 5/168 (20060101) |
Field of
Search: |
;128/202.22,207.15,207.14 ;600/437 ;181/126,70,139 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Philips; Bradley
Assistant Examiner: Leszczak; Victoria
Attorney, Agent or Firm: McKinney, Esq.; Matthew G. Allen,
Dyer, Doppelt, Milbrath & Gilchrist P.A.
Parent Case Text
I. CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application
No. 61/606,679 filed Mar. 5, 2012. The disclosure of the
provisional application is incorporated herein by reference.
Claims
What is claimed is:
1. A leak detection method for tube placement, the method
comprising: using a microphone at only one location coupled to the
tube to detect acoustic waves generated by vibrations from a
passage of air between an inflatable cuff of the tube and an
anatomical conduit when inserted in the anatomical conduit; and
transmitting the acoustic waves from the microphone at the only one
location to a processor that is configured to compare the acoustic
waves to a baseline expected sound profile stored in a memory and
determine that a leak around the inflatable cuff is present when
the acoustic waves are in addition to the baseline expected sound
profile, wherein the baseline expected sound profile is established
by the detection of a frequency range over a duration of time, such
that the expected baseline sound profile defines an absence of a
backflow of the air and other fluids caused by leakage past the
cuff.
2. The leak detection method of claim 1, further comprising:
causing the processor to operate an inflation device to renew a
seal between the inflatable cuff and the anatomical conduit if the
processor detects the leak.
3. The leak detection method of claim 1, further comprising
manually adjusting an inflation device to adjust a pressure in the
inflatable cuff until the leak has stopped.
4. The leak detection method of claim 1, further comprising using
the detected acoustic waves as a feedback mechanism when
pressurizing the inflatable cuff, such that when the leakage has
stopped, a level of pressure of the inflatable cuff is recorded and
thereafter adjusted to maintain the pressure at that level.
5. The leak detection method of claim 1, further comprising
coupling the microphone to an external speaker.
6. The leak detection method of claim 1, further comprising
initially pressurizing the inflatable cuff secured to a distal end
of the tube to a predetermined level.
7. The leak detection method of claim 2, further comprising
visually displaying at least one baseline expected sound profile
stored in the memory and the detected acoustic waves from the
microphone on a display device.
8. The leak detection method of claim 1, wherein the tube comprises
a catheter.
Description
II. FIELD
The present disclosure is generally related to a leak detection
system and method for tube or catheter placement.
III. DESCRIPTION OF RELATED ART
Endotracheal tubes (hereinafter "ETTs"), often referred to as
breathing tubes, are used to provide a conduit for mechanical
ventilation of patients with respiratory or related problems. An
ETT is inserted through the mouth or nose and into the trachea of a
patient for several reasons: (1) to establish and maintain an open
airway; (2) to permit positive pressure ventilation which cannot be
done effectively by mask for more than brief periods; (3) to seal
off the digestive tract from the trachea thereby preventing
inspiration of forced air into the stomach; and (4) as an
anesthesia delivery system.
ETTs are used extensively in the field, emergency rooms, surgical
suites, and intensive care units for patients that require
ventilatory assistance. During intubation, an ETT is typically
inserted into the mouth, past the vocal cords, and into the
trachea. The proper location of the ETT tip is roughly in the
mid-trachea. However, there are at least three possible undesired
placement positions that can result, either during intubation or
due to a subsequent dislodgment. One of these positions is in the
esophagus. Another undesired position occurs from over-advancement
of the ETT past the bifurcation of the trachea (carina) and into
one of the mainstem bronchi. A third is above the vocal cords in
the vocal tract.
The structure of the human airways is extremely complex. At the
upper end of the trachea is the larynx containing the vocal folds,
and at the lower end is the first bifurcation, known as the carina.
The adult trachea is approximately 1.4 to 1.6 cm in diameter and 9
to 15 cm long. The newborn trachea averages about 0.5 cm in
diameter and 4 cm in length. The airways that are formed by the
carina are the right primary bronchus and the left primary
bronchus. The right primary bronchus is shorter, wider, and more
vertical than the left primary bronchus. For this reason a majority
of erroneous ETT insertions past the carina tend to follow the
right primary bronchus. Continuing farther down the airways, the
bronchi branch into smaller and smaller tubes. They finally
terminate into alveoli, small airfilled sacs where oxygen-carbon
dioxide gas exchange takes place.
Providing a correctly positioned and unobstructed endotracheal tube
is a major clinical concern. Any misplacement or obstruction of an
ETT can pose a threat to the patient's health. Misdirecting the ETT
into the esophagus or locating the tip where there is a significant
obstruction of its lumen can result in poor ventilation of the
patient and eventually lead to cardiac arrest, brain damage or even
death. Further, if the ETT is misplaced into a mainstem bronchus,
lung rupture can occur.
In an attempt to avoid possible complications with ETT use, several
techniques have been developed to aid clinicians in the proper
placement/location of ETTs. Guidelines for the ideal technique are
as follows: (1) the technique should work as well for difficult
intubations as it does for those not so difficult; (2) the
technique should indicate a proper ETT tip location unequivocally;
(3) esophageal intubation must always be detected; and (4)
clinicians must understand the technique and how to use it. The
known techniques for clinical evaluation of ETT location include
direct visualization of the ETT placement, chest radiography,
observation of symmetric chest movements, auscultation of breath
sounds, reservoir bag compliance, the use of a video stethoscope,
fiberoptic bronchoscopy, pulse oximetry, and capnometry. However,
none of the listed techniques allow a health care provider to
constantly monitor the precise location of an ETT within the
trachea, or the degree of obstruction of its lumen.
Another challenge with placing the ETT in the trachea for
ventilation is an undesirable backflow of air around the ETT, since
such backflow reduces the amount of positive ventilation pressure
that can be maintained in the lungs. To address this challenge, a
cuff can be adapted to seal against the inner diameter of the
trachea. However, as the tracheal walls move, leaks can still
occur. In addition, post-placement movement of the ETT within the
trachea can also cause leaks around the ETT. In some embodiments,
the cuff may be inflated with a fluid (such as air) in order to
form the seal. A cuff pressure that is too high can collapse the
blood capillaries in the wall of the trachea and cause necrosis. A
cuff pressure that is too low may provide an inadequate seal and
result in both a reduction of positive ventilation pressure and an
increased likelihood of fluid from the proximal side of the cuff
(such as accumulated patient secretions) to leak into the lungs,
raising the possibility of the patient contracting pneumonia.
Apparatuses and methods for acoustically guiding, positioning, and
monitoring tubes within a body are known in the art. See, for
example, U.S. Pat. Nos. 5,445,144 and 6,705,319 to Wodicka et al.,
incorporated herein by reference, which disclose an apparatus and
method for acoustically monitoring the position of a tube within an
anatomical conduit. In various embodiments, a sound pulse is
introduced into a wave guide and is recorded as it passes by one or
more microphones located in the wave guide wall. After propagating
down the ETT, the sound pulse is emitted through the distal tip of
the ETT into the airway (or wherever in the body the tip of the ETT
is located) and an acoustic reflection propagates back up the ETT
to the wave guide for measurement by the same microphone(s). The
amplitude and the polarity of the incident and reflected sound
pulse are used to estimate the characteristics of the airway and
the ETT, and thereby guide the ETT placement or monitor the ETT for
patency.
As disclosed by Wodicka, et al., the acoustical properties of the
airways of a respiratory system change dramatically over the
audible frequency range. At very low frequencies, the large airway
walls are yielding and significant wall motion occurs in response
to intra-airway sound. In this frequency range, the airways cannot
be represented accurately as rigid conduits and their overall
response to sonic pulses is predictably complex. At very high
audible frequencies, the large airway walls are effectively more
rigid due to their inherent mass. However, one-dimensional sound
propagation down each airway segment cannot be ensured as the sonic
wavelengths approach in size the diameter of the segment, and
effects of airway branching are thought to increase in importance.
There appears to be a finite range of frequencies between roughly
500 and 6,000 Hz where the large airways behave as nearly rigid
conduits and the acoustical effects of the individual branching
segments are not dominant. It is over this limited frequency range
where the complicated branching network can be approximately
represented as a flanged "horn" and where its composite acoustical
properties reflect the total cross-sectional area of the
airways.
Accordingly, there is a need for an improved method and system for
acoustically sensing a leak in the seal between a tube or catheter
within a body and the body cavity against which it is sealed and to
assist the user in adjusting the system until the leak has been
substantially sealed. In addition, there is a need for establishing
system parameters to be used thereafter to maintain the system in
an operating state that will substantially prevent leakage, all
using a noninvasive acoustic technique. However, in view of the
prior art at the time the present invention was made, it was not
obvious to those of ordinary skill in the pertinent art how the
identified needs could be fulfilled.
IV. SUMMARY
A leak detection system and method for tube or catheter placement
is disclosed. The system and method of the present disclosure
conveniently utilize the microphone in the waveguide connected to
the ETT to detect sounds indicative of leakage past the ETT cuff.
Alternatively, another microphone independent of the microphone
used to guide placement of the ETT may be used. The noninvasive
system and method of the present disclosure are therefore able to
assist the user in creating an adequate seal between the ETT and
the trachea (or between any other tube or catheter and a body
cavity into which it has been inserted) and assist in maintaining
the seal once it has been established. Furthermore, the system has
no moving parts, and can be easily understood and operated by
skilled clinicians.
According to one aspect of the present disclosure, the system may
be configured for acoustically detecting the sounds caused by
fluids (such as air or other gases) leaking past a cuff sealing a
tube or catheter against the walls of an anatomical conduit.
Detection of these sounds, either by a human operator or by an
automated system employing a processing device, can be used to warn
a user of the system that a leak is occurring, and in other
embodiments can automatically initiate adjustment of the system in
order to stop the leak. For example, the system may include a
microphone for detecting sounds in or near the tube and for
generating a first signal corresponding to the detected sound, a
speaker for creating an audible version of the first signal, where
a user can listen to the audible version and determine if
adjustments to the leakage prevention cuff are needed.
In another particular embodiment, the system may include the
microphone for detecting sounds in or near the tube and for
generating a first signal corresponding to the detected sound, and
a processor configured to receive the first signal and to
discriminate between an expected baseline representing normal
sounds in or near the tube and unexpected sounds representative of
leakage past the cuff, where the processor using the first signal
to report that a leak has been detected. The processor may be
further configured to detect that a leak is present and to then
control an inflation device to automatically increase the pressure
in the leak prevention cuff. In addition, the tube may be adapted
to be coupled to a medical device, such as a mechanical ventilator,
a breathing bag, an anesthesia machine, or an infusion pump.
Further, a display may be provided in electronic communication with
the processor.
In yet another illustrative embodiment, a method of acoustically
detecting a leak past a cuff sealing a tube to a body is disclosed.
The method includes detecting a sound in or near the tube, and
audibly presenting the detected sound to a user of the tube for
determination of whether a leak is present. In one aspect of this
embodiment, the method further includes applying the detected sound
signal to a processor that is configured to analyze the sound and
detect the sound of a leak over a baseline expected sound profile.
The method may also include causing the processor to operate an
inflation device to renew the seal between the tube and the
anatomical conduit if the processor detects a leak. In yet another
aspect of this method, the detected sound may be used as a feedback
mechanism when pressurizing the cuff, such that when the detected
sound indicates that the leakage has stopped, the pressure of the
cuff can be recorded and thereafter adjusted to maintain the
pressure at that level.
Additional objects, features, and advantages of the present
disclosure will become apparent to those skilled in the art upon
consideration of the following detailed description of a preferred
embodiment exemplifying the best mode of carrying out the teachings
of the present disclosure as presently perceived.
V. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatical view of a prior art system for
determining characteristics of an unknown system;
FIG. 2 is a diagrammatical view of a prior art two-microphone
system for determining characteristics of an unknown system;
FIG. 3 is a diagrammatical view illustrating proper insertion of an
endotracheal tube (ETT) into a trachea of a human body;
FIG. 4 is a diagrammatical view illustrating improper placement of
the ETT into an esophagus;
FIG. 5 is a diagrammatical view illustrating improper placement of
an ETT past a carina and into a right main bronchus;
FIG. 6 is a cross-sectional diagrammatical view of one embodiment
leak detection system;
FIG. 7 is a diagrammatical view of a particular illustrative
embodiment of a leak detection method for tube or catheter
placement; and
FIG. 8 is a flow diagram of a particular embodiment of a leak
detection method for placement of a tube or catheter.
VI. DETAILED DESCRIPTION
For purposes of promoting an understanding of the principles of the
method and system, reference will now be made to the embodiment
illustrated in the drawings, and specific language will be used to
describe that embodiment. It will nevertheless be understood that
no limitation of the scope of the method and system is intended.
Alterations and modifications, and further applications of the
principles of the method and system as illustrated therein, as
would normally occur to one skilled in the art to which the method
and system relates are contemplated, are desired to be protected.
Such alternative embodiments require certain adaptations to the
embodiments discussed herein that would be obvious to those skilled
in the art.
When it is desired to direct an object (such as a tube, catheter,
or other medical device) into an unknown system, it is known to
generate a sound pulse within the tube or medical device and to
receive the reflections of the pulse as they return from the
unknown system, similar to the process used in sonar imaging. In
the case of a system as shown in FIG. 1, a speaker transmits an
incident sound pulse, P.sub.i that travels toward the unknown
system. As the incident sound pulse, P.sub.i, enters the unknown
system, a sound pulse is reflected back, P.sub.r, which can be
received by the microphone. The reflected sound pulse, P.sub.r, can
be analyzed to determine various qualities of the unknown system,
including the cross sectional area of the system. Furthermore, as
the incident sound pulse P.sub.i continues to propagate through the
unknown system, additional reflections may occur. These subsequent
reflected sound pulses can indicate additional qualities of the
unknown system, such as the depth of the system, and whether the
cross sectional area changes at all throughout that depth.
A two-microphone system is shown in FIG. 2, where the two
microphones are separated by a distance d. In the two-microphone
system, determination can be made as to the direction of travel of
a sound pulse, P.sub.i or P.sub.r, by analyzing the difference
between the instant in which the sound pulse is detected by the
first microphone M1, and the instant in which the sound pulse is
detected by the second microphone, M2. For example, if a sound
pulse is first detected by M1 and then by M2, the pulse is
determined to be traveling away from the unknown system, and is
thus a reflected pulse P.sub.r. In contrast, if a sound pulse is
first detected by M2 and then M1, the pulse is determined to be
traveling toward the unknown system.
The directional determination of the traveling sound pulse prevents
the misreading of incident sound pulses that are reflected from the
speaker end, SE, of the tube, such as P.sub.ir. For various
reasons, an incident sound pulse, P.sub.i, may be reflected from
the speaker end, SE, of the tube, including the presence of a
blockage in the tube, a wall at the end of the tube, or the
attachment of another device (i.e. a mechanical ventilator) to the
end of the tube. False readings can occur when reflected sound
pulse, P.sub.ir, travels past a single microphone, such as that
shown in FIG. 1. However, when two microphones are used, such as in
the system illustrated in FIG. 2, a determination of the direction
of travel of the reflected sound pulse, P.sub.ir, can eliminate the
possibility of a misreading.
Although the method and system described below relate to
maintaining a seal between an endotracheal tube (ETT) and a portion
of a respiratory system of a body, it should be understood that the
system and methods of the present disclosure may be used to
maintain a seal between gas or liquid filled tubes or catheters and
other anatomical conduits or cavities.
As mentioned above, a method and system for guiding the positioning
of an ETT is known in the art. For a description of a single
microphone system for guiding the insertion of the ETT, and a more
detailed description of the analysis and theory involved in
determining the position of the ETT, reference can be made to U.S.
Pat. No. 5,455,144 to Wodicka, et al., previously incorporated by
reference. For a description of a two-microphone system for guiding
the insertion of the ETT, and a more detailed description of the
analysis and theory involved in determining the position of the
ETT, reference can be made to U.S. Pat. No. 6,705,319 to Wodicka,
et al., previously incorporated by reference.
Referring now to the drawings, FIGS. 3-5 illustrate insertion of an
ETT 10 into a human body 12. ETT 10 includes a hollow tube having a
distal end 14 for insertion into body 12 and a connector 16 located
outside body 12. Illustratively, ETT 10 is inserted into a mouth 18
of the patient. A respiratory system 20 includes a trachea 22 which
extends between vocal folds 24 of a larynx and a first bifurcation
known as a carina 26. Airways formed by carina 26 include a right
primary bronchus 28 and a left primary bronchus 30. Continuing
farther down the airway, bronchial tubes branch into smaller and
smaller tubes,
FIG. 3 illustrates proper insertion of ETT 10 into trachea 22
between vocal folds 24 and carina 26. For proper mechanical
ventilation of the patient, it is important that distal end 14 of
ETT 10 is positioned properly within trachea 22 between vocal folds
24 and carina 26 to provide adequate ventilation to both lungs 32
and 34. An inflatable cuff 35 provides a seal between the ETT 10
and the airway, as described in greater detail hereinbelow.
Insertion of ETT 10 into the trachea 22 is sometimes a difficult
procedure. As illustrated in FIG. 4, it is possible for distal end
14 of ETT 10 to miss the entrance to trachea 22 and enter an
esophagus 36 leading to the stomach (not shown). Improper placement
of ETT 10 into the esophagus is most evident in a pre-hospital or
emergency room setting which is characterized by high stress and
limited time. Improper placement of open distal end 14 of ETT 10
into the esophagus 36 prevents ventilation of lungs 32 and 34.
Improper insertion of distal end 14 of ETT 10 past carina 26 will
result in ventilation of only right lung 32 or left lung 34. FIG. 5
illustrates improper insertion of distal end 14 of ETT 10 past
carina 26 and into right main bronchus 28. Because right primary
bronchus 28 is shorter, wider, and more vertical than left primary
bronchus 30, the majority of ETT insertions past carina 26 tend to
follow the right primary bronchus 28. The speaker/microphone
guidance systems disclosed in U.S. Pat. Nos. 5,455,144 and
6,705,319 to Wodicka, et al, detect if ETT 10 is improperly
inserted into esophagus 36, right primary bronchus 28, or left
primary bronchus 30 and alert a user to the improper placement. The
apparatus can then be used to guide movement of ETT 10 back into
its proper position within trachea 22.
According to some embodiments of the present disclosure, the ETT 10
may be equipped with a cuff 35 as shown in FIG. 6. The cuff 35,
known to a person having ordinary skill in the art, is coupled to a
tubular portion 204 of the ETT 10 near the distal end 14. In FIG.
6, the ETT 10 is shown inserted into a body cavity, such as a
trachea 22. The cuff 35 is configured to be a flexible member. In
one form, the cuff 35 is formed in a substantially toroidal form,
having any desired cross-sectional shape such as circular, oval,
square or rectangular, to name just a few non-limiting examples.
Pressurizing the interior of the cuff 35 with a gas or fluid can
adjust an outer diameter (identified by reference numeral 210) of
the cuff 35 with respect to an inner diameter (identified by
reference numeral 208), thereby determining the pressure with which
the cuff 35 presses against both the tubular portion 204 of the ETT
10 and the walls of the trachea 22. The inner portion of the cuff
35 is coupled to the outer surface of the tubular portion 204. The
cuff 35 can be permanently coupled to the tubular portion 204,
e.g., by being molded to or glued to the tubular portion 204, or in
other manners that will be apparent to those skilled in the art in
view of the present disclosure.
The cuff 35 may be in communication with an inflation device 225.
In one embodiment, the inflation device 225 comprises a one-way
valve 220 to which a syringe 221 (or other appropriate device) may
be attached. The inflation device 225 can be configured to inflate
the cuff 35 for an improved sealing against the anatomical conduit
such as the trachea 22. Syringe 221 contains a gas or fluid 222
that may be injected to, or withdrawn from, the cuff 35 through the
tube 224 by actuation of the plunger 226. Once inflated, the
syringe 221 may be optionally disconnected from the one-way valve
220. Other devices known in the art may be used as an inflation
device 225, such as a pump, for example.
The cuff 35, when properly pressurized, is configured to prevent
backflow of air, or other fluids (e.g., blood, mucous, liquid and
gaseous compounds, etc.), collectively referred to hereunder as air
or other fluids, between the tubular portion 204 of the ETT 10 and
the trachea 22, or other anatomical structures, collectively
referred to hereunder as anatomical conduits, with which the ETT 10
or other tubular device is used to transfer air or other fluids
therein. Such a backflow is undesired in ventilation and other
applications in which the air or other fluids are introduced
through the ETT 10 to an anatomical conduit, as it is desired to
maintain a positive pressure within the anatomical conduit. In the
case of an ETT 10 positioned within a trachea 22, the cuff 35
performs the further function of preventing the flow of accumulated
fluids that may be proximal to the cuff 35 past the cuff 35 and
into the lungs. Such unintended flow can cause pneumonia in the
patient.
The undesirable passage of the air or other fluids between the cuff
35 and the anatomical conduit generates vibrations. The vibrations
can generate waves that can be sensed by a detection device 80 that
may include a pressure sensor 74, the first microphone 76 and/or
the second microphone 78. The microphone(s) 76, 78 may be coupled
to an external speaker or headphones through an appropriate
optional amplifier so that a user can listen for the sound made by
the fluid leaking past the cuff 35. In one embodiment, the
inflation device 225 is operated to increase the pressure in the
cuff 35 until the user detects that the sound generated by the
leakage past the cuff 35 has stopped or substantially stopped. An
appropriate pressure sensor of the cuff 35 (and/or the inflation
device 225) may sense a cuff pressure and record the cuff pressure
at this point in time and adjustment of the cuff pressure using the
inflation device 225 may be made throughout the remaining time that
the ETT 10 is inserted in order to maintain the cuff 35 at that
pressure. Such monitoring and maintenance of the appropriate
pressure may be done manually by the operator, or under the control
of a computer or other processing device as will be appreciated by
those skilled in the art in view of the present disclosure. For
example, an automated system may be used to maintain the cuff 35
pressure at a set point, and that set point may be determined by
acoustic feedback identifying the presence or absence of sound
leaking past the cuff 35.
In some embodiments, two microphones (such as those illustrated in
FIGS. 2 and 6), may be used in order to help identify the sounds
indicative of leakage past the cuff 35. As described hereinabove,
two microphones 76, 78 may be used to determine the direction of
travel of a sound. Using such techniques, the system may
differentiate between sounds that arise from the machine (e.g.,
ventilator) end from those that arise from the patient end. The
system may use this information to verify that the sound identified
as noise leaking past the cuff 35 is indeed propagating in a
direction coming from the cuff 35 to the microphones 76, 78 using a
temporal analysis or other appropriate analysis.
In other embodiments, the cuff 35 can be initially filled to a
predetermined pressure (such as a pressure recommended by the
manufacturer of the ETT 10). Thereafter, the microphones 76, 78 can
be used to monitor for a leak past the cuff 35 and, if detected,
the inflation device 225 can be used to increase the pressure in
the cuff 35 until the leakage is heard to cease or substantially
cease.
In other embodiments, the leak detection may also be automated,
with a detection system configured to detect vibrations generated
due to the backflow of the air or other fluids. In other
embodiments, the processor may have direct control of the operation
of the inflation device 225 and can automatically adjust the
pressure in the cuff 35.
Referring to FIG. 7, a particular illustrative embodiment of a leak
detection system is depicted and generally designated 300. As
described above, the ETT 10 may be inserted into the anatomical
conduit, such as a trachea 22 and equipped with a cuff 35. The
pressure of the cuff 35 can be increased and decreased to adjust to
an outer diameter of the cuff 35 to press against the ETT 10 and
the walls of the trachea 22. The system 300 includes a processor
304 that is communication with a vibration detection device 80
configured to detect acoustic waves generated by vibrations caused
by a leak of fluids between the cuff 35 and an anatomical conduit
22. In addition, the tube 10 may be adapted to be coupled via
connector 16 to a medical device 90, such as a mechanical
ventilator, a breathing bag, an anesthesia machine, or an infusion
pump. A memory 306 of a computer 302 may be configured to store
baseline expected sound profile(s) 308. An analysis module 310 may
be used to determine whether signals received from the microphones
76, 78 of the vibration detection device 80 indicate a leak around
the cuff 35 when compared to the expected sound profiles 308. In
addition, an output device 312 may be in direct communication with
the computer 302, where the output device 312 is able to render an
audio alert, visual alert, or any combination thereof. For example,
a cathode ray tube (CRT) display, liquid crystal display (LCD),
light emitting diode (LED) display, plasma display, or other
display device that is accessible to the processor 304 to display a
visual rendering of the expected sound profiles 308 and the signals
received from the microphones 76, 78.
An inflation device 225 may be in communication with the cuff 35
via tube 224 and the computer 302. The sound profile(s) 308 and
analysis module 310 may be implemented in hardware, firmware,
software, other programmable logic, or any combination thereof. The
memory 306 includes media that is readable by the processor 304 and
that stores data and program instructions that are executable by
the processor 304.
In operation, the sound profile exhibited by air or other fluids
leaking past the cuff 35 may be characterized, such as vibrations
within a defined frequency range detected over a minimum window of
time. The processor 302 of the detection system 300 is programmed
to analyze the signals generated by one or more microphones 76, 78
of the vibration detection device 80, and to detect a sound pattern
matching the known leakage sound profile 308. In an alternative
embodiment, a baseline is established for normal passage of the air
or other fluids, i.e., absence of a backflow of the air or other
fluids caused by leakage past the cuff 35, and a processor 304 of
the detection system 300 is programmed to analyze signals generated
by at least one the microphone 76 or 78. The processor 304 can then
be programmed to recognize vibrations caused due to the backflow of
the air or other fluids, such vibrations being in addition to the
expected baseline vibrations. When the processor 304 identifies the
air or other fluids are leaking due to the backflow, the processor
304 can then provide an audio and/or visual alert to an operator to
take corrective actions.
A flow diagram of a particular embodiment of a leak detection
method is described in FIG. 8. At 400, a sound in or near a tube
that is inserted in an anatomical conduit is detected using a
microphone. The sound may be generated from a speaker within the
tube or acoustic waves generated by vibrations caused by a leak of
fluids between a cuff and an anatomical conduit. Moving to 402, the
detected sound may be audibly presented to an operator of the tube
for determination of whether a leak around a cuff of the tube is
present. In addition, or alternatively, the detected sound signal
may be transmitted, at 404, to a processor that is configured to
analyze the sound and detect the sound of the leak over a baseline
expected sound profile. The processor is configured to operate and
cause an inflation device to renew a seal between the tube and the
anatomical conduit if the processor detects the leak, at 406. The
detected sound may be used as a feedback mechanism when
pressurizing the cuff, at 408, such that when the detected sound
indicates that the leakage has stopped, a level of pressure of the
cuff is recorded and thereafter adjusted to maintain the pressure
at the level.
Although the system and method described is related to maintaining
a seal around an ETT 10 within a respiratory system of a body, it
is understood that the system and method of the present disclosure
may be used to maintain seals around gas or liquid filled tubes or
catheters into other body cavities or in various mechanical
operations. The leak detection system and method can be applied to
a wide variety of clinical tubes or catheters where maintenance of
a seal therearound is required.
Although the teachings of the present disclosure have been
described in detail with reference to certain embodiments,
variations and modifications exist within the scope and spirit of
these teaching as described and defined in the following
claims:
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